MYTH: Activated charcoal is a superfood.

Eating and even brushing your teeth with activated charcoal is the latest trend within the superfood craze.showcake/Shutterstock

Activated charcoal is not quite as super as its super-fans would have you believe.

"Activated charcoal is known for its absorption properties ... but it can also deplete your system of good nutrients your body needs," dietitian Grace Derocha, a wellness coach at Blue Cross Blue Shield of Michigan, told INSIDER. "Activated charcoal supplements may diminish the effectiveness of medications people take as well." (That includes birth control pills.)

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MYTH: Artificial sweeteners are better than the alternative.

Artificial sweeteners are usually thought to be better because they're low in sugar, and totally sugar-free.Steve Snodgrass / Flickr

MYTH: Carbs are the enemy.

Gluten-free and low-carb diets perpetuate some of the most pervasive health myths out there.Paul Sakuma / AP

We already know that gluten-free diets are a bad idea, but Derocha emphasizes that not all carbs are created equal. "Complex carbs found in whole grain or whole wheat foods contain healthy levels of nutrients and fiber," she said. "Simple carbohydrates like white rice and white bread are the type that cause issues due to their lack of nutrients."

MYTH: Cravings mean you have a nutritional deficiency.

When you crave meat or dairy, the (not-so) old wives' tale indicates that your body is trying to tell you something.Photo and Share CC/Flickr

"It is difficult to conclusively say that cravings are connected to nutritional deficiencies," Derocha said. "Often, it's a way for people to justify eating certain foods."

For instance, some people say that a chocolate craving indicates that you need magnesium. But there are several foods that are richer in magnesium than chocolate (like pumpkin seeds and tofu) that you don't see many people craving.

Derocha did say that cravings could actually be a little-known sign of dehydration, so keep drinking water.

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MYTH: Eating after 6 p.m. is a bad idea.

Eating at night has always had bad connotations associated with it.Getty Images

"This is a persistent myth," Frida Harju, a nutritionist at the health app Lifesum, told INSIDER. "Your body won't know what time it is, whether it is 6 or 7 p.m.. What it does know is how many calories you consume." She suggests instead of putting a cutoff time on your meals, to eat smaller portions instead.

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MYTH: Eating fats will make you fat.

For decades, fats were seen as the enemy of good health, but now nutritionists are doing an about-face on this advice.Iurii Stepanov/Shutterstock

"Fat is a necessary element in our diets, as the body can't process some vitamins without the fat's help in dissolving them into your system," Harju said. "It's important not to cut out all fats from your diet, but instead, know the difference between the healthy and unhealthy varieties."

MYTH: Some types of sugar are better for you than others.

Natural sweeteners aren't really better for you than more refined ones. A tablespoon of honey, maple syrup, and white sugar all provide roughly the same amount of sugar with essentially no additional nutrients. Your body doesn't recognize any differences between them.

"There's this idea that there are different types of sugar, but that's a myth," cardiologist Jennifer Haythe told INSIDER in September. "Brown sugar, white sugar, honey [...] they are all ultimately broken down into the same thing: glucose." (This is just one of many pervasive myths about sugar.)

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MYTH: Frozen vegetables aren’t as healthy as fresh vegetables.

Frozen vegetables get a bed reputation because fresh vegetables just sound better for you.miran/Flickr

This is a tricky one. Sometimes fresh produce does have more nutrients than frozen, but often fresh produce loses some of its nutrients through exposure to oxygen and sunlight, according to Harju.

"A good rule of thumb is to buy frozen produce when it isn't in season and fresh, local produce when in season," she advised.

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MYTH: Juice cleanses can detox your system.

Juice cleanses are the most popular type of detox that's supposed to clear your body of noxious "toxins."Tamara Smith / Flickr

Plus, juice cleanses can actually be dangerous because they eliminate important nutrients and calories. They can actually force your body to go into starvation mode, according to Derocha. That's why you lose weight so fast when you go on a "detox" program. Unfortunately, you'll likely gain back every pound as soon as the cleanse is over.

"Your best bet is to count on your body's natural cleansing mechanisms, consume nutrient-dense food, stay active, control portions and drink plenty of water," she said.

Some people swear that gluten-free diets make them feel better. But experts suspect that good feeling is probably the result of overall healthier eating— say, replacing gluten-filled doughnuts with oatmeal and fresh fruit. Gluten doesn't have anything to do with it.

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MYTH: You need to drink eight glasses of water a day.

The "eight glasses of water a day" mantra has been drilled into our heads, but hardly anyone actually follows it.David von Diemar/Unsplash

Your body does need significant amounts of water to survive and thrive, but there's no real science behind the old eight-glasses-a-day belief. And there are other ways to stay hydrated besides plain old H2O.

"We can get some of the required liquid from other drinks, such as tea, coffee, and fruits and vegetables," Harju said.

The best way to determine if you're adequately hydrated is to look at your urine. If it looks like pale lemonade, you're good. If it's darker — more like apple juice — you need more fluid.

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MYTH: You should eat seven small meals every day.

So the myth goes: it's better to eat several small meals or snacks every day than to indulge in three normal-sized meals.Photo-Dave/iStock

The truth is that it might work for you, but it might not.

"Everyone's body and metabolism are different, so this approach cannot be considered a viable go-to option in every case," Derocha said. The best thing to do is to be mindful of portion size and never skip meals, she added.

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MYTH: Everyone should count calories.

When it comes to calories, both quantity and quality matter.Shutterstock

Calorie-counting is the backbone of popular diets like CICO— Calories In, Calories Out — that some people swear by.

But calories don't tell the whole story about a food. An ounce of almonds has more calories than an ounce of pretzels, but the almonds have more nutrients, fiber, and protein. If you judged by calorie content alone, you might have picked the pretzels.

Experts say you should consider calories and overall nutritional quality.